This happens on Windows and macOS too, no sure what to do.

mozilla@mozillas-Air gecko % ./mach vendor python
Site not up-to-date reason: "/Users/mozilla/Documents/GitHub/gecko/obj-aarch64-apple-darwin21.6.0/_virtualenvs/vendor" does not exist
created virtual environment CPython3.9.6.final.0-64 in 173ms
  creator CPython3macOsFramework(dest=/Users/mozilla/Documents/GitHub/gecko/obj-aarch64-apple-darwin21.6.0/_virtualenvs/vendor, clear=False, no_vcs_ignore=False, global=False)
  activators BashActivator,CShellActivator,FishActivator,PowerShellActivator,PythonActivator
Collecting poetry==1.2.0a2
  Downloading poetry-1.2.0a2-py3-none-any.whl (190 kB)
     |████████████████████████████████| 190 kB 1.6 MB/s 
Requirement already satisfied: requests<3.0,>=2.18 in ./third_party/python/requests (from poetry==1.2.0a2) (2.25.1)
Collecting cachy<0.4.0,>=0.3.0
  Downloading cachy-0.3.0-py2.py3-none-any.whl (20 kB)
Collecting shellingham<2.0,>=1.1
  Downloading shellingham-1.5.0-py2.py3-none-any.whl (9.3 kB)
Requirement already satisfied: packaging<21.0,>=20.4 in ./third_party/python/packaging (from poetry==1.2.0a2) (20.9)
Collecting pexpect<5.0.0,>=4.7.0
  Downloading pexpect-4.8.0-py2.py3-none-any.whl (59 kB)
     |████████████████████████████████| 59 kB 16.8 MB/s 
Collecting requests-toolbelt<0.10.0,>=0.9.1
  Downloading requests_toolbelt-0.9.1-py2.py3-none-any.whl (54 kB)
     |████████████████████████████████| 54 kB 9.7 MB/s 
Collecting pkginfo<2.0,>=1.5
  Downloading pkginfo-1.8.3-py2.py3-none-any.whl (26 kB)
Collecting poetry-core<2.0.0,>=1.1.0a6
  Downloading poetry_core-1.3.2-py3-none-any.whl (531 kB)
     |████████████████████████████████| 531 kB 19.2 MB/s 
Collecting cachecontrol[filecache]<0.13.0,>=0.12.4
  Downloading CacheControl-0.12.11-py2.py3-none-any.whl (21 kB)
Collecting html5lib<2.0,>=1.0
  Using cached html5lib-1.1-py2.py3-none-any.whl (112 kB)
Collecting entrypoints<0.4,>=0.3
  Downloading entrypoints-0.3-py2.py3-none-any.whl (11 kB)
Collecting crashtest<0.4.0,>=0.3.0
  Downloading crashtest-0.3.1-py3-none-any.whl (7.0 kB)
Collecting keyring>=21.2.0
  Downloading keyring-23.9.3-py3-none-any.whl (35 kB)
Collecting cleo<2.0.0,>=1.0.0a4
  Downloading cleo-1.0.0a5-py3-none-any.whl (78 kB)
     |████████████████████████████████| 78 kB 30.1 MB/s 
Collecting tomlkit<1.0.0,>=0.7.0
  Downloading tomlkit-0.11.5-py3-none-any.whl (35 kB)
Collecting virtualenv<20.4.5,>=20.4.3
  Downloading virtualenv-20.4.4-py2.py3-none-any.whl (7.2 MB)
     |████████████████████████████████| 7.2 MB 18.6 MB/s 
Collecting msgpack>=0.5.2
  Downloading msgpack-1.0.4-cp39-cp39-macosx_11_0_arm64.whl (69 kB)
     |████████████████████████████████| 69 kB 31.1 MB/s 
Collecting lockfile>=0.9
  Downloading lockfile-0.12.2-py2.py3-none-any.whl (13 kB)
Collecting pylev<2.0.0,>=1.3.0
  Downloading pylev-1.4.0-py2.py3-none-any.whl (6.1 kB)
Requirement already satisfied: six>=1.9 in ./third_party/python/six (from html5lib<2.0,>=1.0->poetry==1.2.0a2) (1.13.0)
Collecting webencodings
  Using cached webencodings-0.5.1-py2.py3-none-any.whl (11 kB)
Collecting jaraco.classes
  Downloading jaraco.classes-3.2.3-py3-none-any.whl (6.0 kB)
Collecting importlib-metadata>=3.6
  Downloading importlib_metadata-5.0.0-py3-none-any.whl (21 kB)
Requirement already satisfied: zipp>=0.5 in ./third_party/python/zipp (from importlib-metadata>=3.6->keyring>=21.2.0->poetry==1.2.0a2) (3.4.1)
Requirement already satisfied: pyparsing>=2.0.2 in ./third_party/python/pyparsing (from packaging<21.0,>=20.4->poetry==1.2.0a2) (2.4.7)
Collecting ptyprocess>=0.5
  Downloading ptyprocess-0.7.0-py2.py3-none-any.whl (13 kB)
Requirement already satisfied: idna<3,>=2.5 in ./third_party/python/idna (from requests<3.0,>=2.18->poetry==1.2.0a2) (2.10)
Requirement already satisfied: chardet<5,>=3.0.2 in ./third_party/python/chardet (from requests<3.0,>=2.18->poetry==1.2.0a2) (4.0.0)
Requirement already satisfied: urllib3<1.27,>=1.21.1 in ./third_party/python/urllib3 (from requests<3.0,>=2.18->poetry==1.2.0a2) (1.26.0)
Requirement already satisfied: certifi>=2017.4.17 in ./third_party/python/certifi (from requests<3.0,>=2.18->poetry==1.2.0a2) (2018.4.16)
Collecting filelock<4,>=3.0.0
  Downloading filelock-3.8.0-py3-none-any.whl (10 kB)
Requirement already satisfied: appdirs<2,>=1.4.3 in ./third_party/python/appdirs (from virtualenv<20.4.5,>=20.4.3->poetry==1.2.0a2) (1.4.4)
Collecting distlib<1,>=0.3.1
  Downloading distlib-0.3.6-py2.py3-none-any.whl (468 kB)
     |████████████████████████████████| 468 kB 47.5 MB/s 
Collecting more-itertools
  Downloading more_itertools-8.14.0-py3-none-any.whl (52 kB)
     |████████████████████████████████| 52 kB 7.7 MB/s 
Installing collected packages: msgpack, more-itertools, webencodings, pylev, ptyprocess, lockfile, jaraco.classes, importlib-metadata, filelock, distlib, crashtest, cachecontrol, virtualenv, tomlkit, shellingham, requests-toolbelt, poetry-core, pkginfo, pexpect, keyring, html5lib, entrypoints, cleo, cachy, poetry
  Attempting uninstall: importlib-metadata
    Found existing installation: importlib-metadata 1.7.0
    Not uninstalling importlib-metadata at /Users/mozilla/Documents/GitHub/gecko/third_party/python/importlib_metadata, outside environment /Users/mozilla/Documents/GitHub/gecko/obj-aarch64-apple-darwin21.6.0/_virtualenvs/vendor
    Can't uninstall 'importlib-metadata'. No files were found to uninstall.
Successfully installed cachecontrol-0.12.11 cachy-0.3.0 cleo-1.0.0a5 crashtest-0.3.1 distlib-0.3.6 entrypoints-0.3 filelock-3.8.0 html5lib-1.1 importlib-metadata-5.0.0 jaraco.classes-3.2.3 keyring-23.9.3 lockfile-0.12.2 more-itertools-8.14.0 msgpack-1.0.4 pexpect-4.8.0 pkginfo-1.8.3 poetry-1.2.0a2 poetry-core-1.3.2 ptyprocess-0.7.0 pylev-1.4.0 requests-toolbelt-0.9.1 shellingham-1.5.0 tomlkit-0.11.5 virtualenv-20.4.4 webencodings-0.5.1
Collecting poetry-core==1.1.0a6
  Downloading poetry_core-1.1.0a6-py3-none-any.whl (421 kB)
     |████████████████████████████████| 421 kB 3.2 MB/s 
Installing collected packages: poetry-core
  Attempting uninstall: poetry-core
    Found existing installation: poetry-core 1.3.2
    Uninstalling poetry-core-1.3.2:
      Successfully uninstalled poetry-core-1.3.2
Successfully installed poetry-core-1.1.0a6
Resolving dependencies... (2.8s)<debug>PackageInfo:</debug> Invalid constraint (0.6 ; extra == 'rq') found in sentry-sdk-0.14.3 dependencies, skipping
Resolving dependencies... (45.0s)

Writing lock file
ERROR: Could not find a version that satisfies the requirement aiohttp==3.7.4.post0appdirs==1.4.4 (from versions: 0.1, 0.2, 0.3, 0.4, 0.4.1, 0.4.2, 0.4.3, 0.4.4, 0.5.0, 0.6.0, 0.6.1, 0.6.2, 0.6.3, 0.6.4, 0.6.5, 0.7.0, 0.7.1, 0.7.2, 0.7.3, 0.8.0, 0.8.1, 0.8.2, 0.8.3, 0.8.4, 0.9.0, 0.9.1, 0.9.2, 0.9.3, 0.10.0, 0.10.1, 0.10.2, 0.11.0, 0.12.0, 0.13.0, 0.13.1, 0.14.0, 0.14.1, 0.14.2, 0.14.3, 0.14.4, 0.15.0, 0.15.1, 0.15.2, 0.15.3, 0.16.0, 0.16.1, 0.16.2, 0.16.3, 0.16.4, 0.16.5, 0.16.6, 0.17.0, 0.17.1, 0.17.2, 0.17.3, 0.17.4, 0.18.0, 0.18.1, 0.18.2, 0.18.3, 0.18.4, 0.19.0, 0.20.0, 0.20.1, 0.20.2, 0.21.0, 0.21.1, 0.21.2, 0.21.4, 0.21.5, 0.21.6, 0.22.0a0, 0.22.0b0, 0.22.0b1, 0.22.0b2, 0.22.0b3, 0.22.0b4, 0.22.0b5, 0.22.0b6, 0.22.0, 0.22.1, 0.22.2, 0.22.3, 0.22.4, 0.22.5, 1.0.0, 1.0.1, 1.0.2, 1.0.3, 1.0.5, 1.1.0, 1.1.1, 1.1.2, 1.1.3, 1.1.4, 1.1.5, 1.1.6, 1.2.0, 1.3.0, 1.3.1, 1.3.2, 1.3.3, 1.3.4, 1.3.5, 2.0.0rc1, 2.0.0, 2.0.1, 2.0.2, 2.0.3, 2.0.4, 2.0.5, 2.0.6.post1, 2.0.7, 2.1.0, 2.2.0, 2.2.1, 2.2.2, 2.2.3, 2.2.4, 2.2.5, 2.3.0a4, 2.3.0, 2.3.1, 2.3.2b2, 2.3.2b3, 2.3.2, 2.3.3, 2.3.4, 2.3.5, 2.3.6, 2.3.7, 2.3.8, 2.3.9, 2.3.10, 3.0.0b0, 3.0.0b1, 3.0.0b2, 3.0.0b3, 3.0.0b4, 3.0.0, 3.0.1, 3.0.2, 3.0.3, 3.0.4, 3.0.5, 3.0.6, 3.0.7, 3.0.8, 3.0.9, 3.1.0, 3.1.1, 3.1.2, 3.1.3, 3.2.0, 3.2.1, 3.3.0a0, 3.3.0, 3.3.1, 3.3.2a0, 3.3.2, 3.4.0a0, 3.4.0a3, 3.4.0b1, 3.4.0b2, 3.4.0, 3.4.1, 3.4.2, 3.4.3, 3.4.4, 3.5.0a1, 3.5.0b1, 3.5.0b2, 3.5.0b3, 3.5.0, 3.5.1, 3.5.2, 3.5.3, 3.5.4, 3.6.0a0, 3.6.0a1, 3.6.0a2, 3.6.0a3, 3.6.0a4, 3.6.0a5, 3.6.0a6, 3.6.0a7, 3.6.0a8, 3.6.0a9, 3.6.0a11, 3.6.0a12, 3.6.0b0, 3.6.0, 3.6.1b3, 3.6.1b4, 3.6.1, 3.6.2a0, 3.6.2a1, 3.6.2a2, 3.6.2, 3.6.3, 3.7.0b0, 3.7.0b1, 3.7.0, 3.7.1, 3.7.2, 3.7.3, 3.7.4, 3.7.4.post0, 3.8.0a7, 3.8.0b0, 3.8.0, 3.8.1, 3.8.2, 3.8.3, 4.0.0a0, 4.0.0a1)
ERROR: No matching distribution found for aiohttp==3.7.4.post0appdirs==1.4.4
Error running mach:

    ['vendor', 'python']

The error occurred in code that was called by the mach command. This is either
a bug in the called code itself or in the way that mach is calling it.
You can invoke |./mach busted| to check if this issue is already on file. If it
isn't, please use |./mach busted file vendor| to report it. If |./mach busted| is
misbehaving, you can also inspect the dependencies of bug 1543241.

If filing a bug, please include the full output of mach, including this error
message.

The details of the failure are as follows:

subprocess.CalledProcessError: Command '['/Users/mozilla/Documents/GitHub/gecko/obj-aarch64-apple-darwin21.6.0/_virtualenvs/vendor/bin/python', '-m', 'pip', 'download', '-r', '/var/folders/0c/tg1wx5wd0fb3r8yywl5wsd0w0000gn/T/tmpxp0q4p1d/requirements.no-markers.txt', '--no-deps', '--dest', '/var/folders/0c/tg1wx5wd0fb3r8yywl5wsd0w0000gn/T/tmpf0b00mbe', '--abi', 'none', '--platform', 'any']' returned non-zero exit status 1.

  File "/Users/mozilla/Documents/GitHub/gecko/python/mozbuild/mozbuild/vendor/mach_commands.py", line 229, in vendor_python
    vendor_command.vendor(keep_extra_files)
  File "/Users/mozilla/Documents/GitHub/gecko/python/mozbuild/mozbuild/vendor/vendor_python.py", line 54, in vendor
    subprocess.check_call(
  File "/Library/Developer/CommandLineTools/Library/Frameworks/Python3.framework/Versions/3.9/lib/python3.9/subprocess.py", line 373, in check_call
    raise CalledProcessError(retcode, cmd)

Sentry event ID: 9b36c1d987a94c908eeeaafbd753b960

./mach vendor python is currently broken (blocked by the Python3.7 upgrade for some CI machines). This particular issue is among the ones fixed in my stack that can't land yet.

I can vendor things directly for you if you need, just let me know what package(s) and I can send you the patch.

Not 100% sure what dependencies I'll use. I'll ping you if things are clear. Thanks!